`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company: 
// Engineer: 
// 
// Create Date:    18:54:18 09/23/2007 
// Design Name: 
// Module Name:    ofdm_modu 
// Project Name: 
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
module ofdm_modem(clk, reset, x_send, x_rec, y_out, , mdm, y_index);
input clk;
input reset;
//聲明了32比特，高16比特是虛部，低16比特是實(shí)部
input [31:0] x_send;
input [31:0] x_rec;
output [31:0] y_out;
output [7:0] y_index; //輸出數(shù)據(jù)的下標(biāo)
output mdm; //標(biāo)志輸出是調(diào)制信號(hào)還是解調(diào)信號(hào),
//1表示調(diào)制信號(hào)，0表示解調(diào)信號(hào)

wire inv_we = 1;
wire [31:0] xn;
wire [49:0] xk;

reg [7:0] cnt;
reg  flag;
wire fwd_inv;

//產(chǎn)生調(diào)制、解調(diào)操作的控制信號(hào)
always @(posedge clk) begin
   if(!reset) begin
	   cnt <= 0;
		flag <= 0;
	end
	   cnt <= cnt + 1;
		if(cnt == 0) 
		   flag <= !flag;
		else
		   flag <= flag;
end

assign fwd_inv = reset ? flag : 0;
//在標(biāo)志為1時(shí)做FFT，完成OFDM信號(hào)的調(diào)制
assign xn[15:0] = flag ? x_send[15:0] : x_rec[15:0];
assign xn[31:16] = flag ? x_send[31:16] : x_rec[31:16];
//由于計(jì)算FFT需要加載數(shù)據(jù)和完成蝶形運(yùn)算兩個(gè)N點(diǎn)的周期，
//所以輸出類型和輸入類型是相反的
assign mdm = !flag;
assign y_out[15:0] = xk[24:9];
assign y_out[31:16] = xk[49:34];

//調(diào)用IPcore
ofdm_fft ofdm_fft(  .fwd_inv_we(inv_we),.start(reset), .fwd_inv(fwd_inv), 
  .clk(clk), .xn_re(xn[15:0]), .xn_im(xn[31:16]),
  .xk_re(xk[24:0]), .xk_im(xk[49:25]), .xk_index(y_index));

endmodule